The continued increase in world population has accentuated the demand for proteins suitable for human food and animal feed. At the same time, use of traditional sources such as fish or livestock is being restricted due to health concern and/or limited supply.
It is well known that certain vegetable crops can provide proteins of high quality. Unfortunately, however, such crops frequently contain harmful and/or bad tasting components that make them unsuitable for food and feed purposes without further treatment. This is especially the case for pulses and in the following soya beans will be used as an example.
Raw soya beans have a content of biologically active proteins known as trypsin inhibitors. They reduce the activity of trypsin which is an enzyme needed in the digestive process. The result is a reduction in nutritional value of the soya-based product. The content of the trypsin inhibitors can be reduced by a heating process, which on the other hand might lead to a reduced value of the soya protein.
Another group of biologically active proteins are the antigens of which the most important are identified as being glycinin and β-conglycinin. They are known to induce serious allergic reactions, especially in young mammals where the digestive tract is not yet fully developed. The known methods to inactivate these proteins are by treating with water-alcohol mixtures and/or by a heating process. The denaturation of the proteins caused by these treatments will result in products with a reduced ability to bind water and fat, as well as overheating may impair the nutritional quality.
The amount and nature of carbohydrates is another group of constituents of concern. Especially the α-1,6-galactosides are of concern as they provoke flatulence and diarrhoea. Means to reduce or eliminate the content of α-1,6-galactosides are extraction with water, degradation by the action of specific enzymes or fermentation. All in all, this is associated with an unfavourable cost benefit ratio.
Furthermore, the palatability of the product is essential for the application of such a product in food and feed. Thus, crude protein products based on pulses are associated with an unpleasant “beany” taste. Processing such as heat treatment add/or extraction with water-alcohol mixtures can reduce this. Commercially available product categories with improved flavour are protein concentrates and isolates.
The main drawbacks of these products are that they are expensive to manufacture and—although they may have a bland taste—they do not possess an attractive flavour on their own that stimulates the appetite. This demonstrates the need for a new type of product, which at the same time is nutritionally optimised and has good functional properties and an attractive flavour.